Cutting down a tree tight between buildings

This guy freaks me out using his saw so carelessly. He seems very adept with it, confident, and that's the freaky part, that's where people get hurt and lose digits. I have not seen anyone set down a chainsaw on a flat surface while it is running. I have not seen anyone leave it running lodged in the tree while they hammer shims into it. He moves all around a saw that is running and he freaks me right out. The chain is disengaged I suppose but it's just insane.